Apparatus for removing liquids from elastomeric polymers

ABSTRACT

A continuous process and apparatus for removing liquids and/or vapors from elastomeric polymers causes the liquid containing polymer to undergo mechanical working and then a substantial reduction in pressure while contained within a chamber having small vents to atmosphere or a collection housing. Essentially all of the last traces of liquids or vapors are removed in this chamber, the material is cooled by the vaporization of contained liquids, any resulting fine particles are contained and immediately mixed into the material, and the material is subsequently discharged through an extruder section without further significant creating of fine particles in the end product as discharged.

[ 51 June 27,1972

22 Filed:

[54] APPARATUS FOR REMOVING LIQUIDS FROM ELASTOMERIC POLYMERS [72]inventor: Robert Kent Slaby, Piqua, Ohio [73] Assignee: The French OilMill Machinery Company,

Piqua, Ohio Sept. 14, 1970 21 Appl. No.: 71,639

Related U.S. Application Data as Continuation-impart of Ser. No.753,647, Aug. '19,

1968, Pat. No. 3,574,891.

52 use ..259/9,l8/12 SB s1 lnt.Cl. .Q ..B01r7/0s 5s FieldofSearch..259/9,l0,25,26,45,46;

18/12 R, 12 SB, 12 SC [56] 9 References Cited UNITED STATES PATENTS3,023,455 3/ 1962 Geier ..259/9 3,382,538 5/1968 Burner .18/12 SB3,505,085 4/1970 Straughn ..259/9 3,601,370 8/1971 Ruettener ..259/9Primary Examiner-Robert W. Jenkins Attorney-Marechal, Biebel, French &Bugg 57 ABSTRACT A continuous process and apparatus for removing liquidsand/or vapors from elastomeric polymers causes the liquid containingpolymer to undergo mechanical working and then a substantial reductionin pressure while contained within a chamber having small vents toatmosphere or a collection housing. Essentially all of the last tracesof liquids or vapors are removed in this chamber, the material is cooledby the vaporization of contained liquids, any resulting fine particlesare contained and immediately mixed into the material, and the materialis subsequently discharged through an extruder section without furthersignificant creating of fine particles in the end product as discharged.

5 Claims, 5 Drawing; Figures PATENTEDJUHN m2 SHEET 2 [1F 2 APPARATUS FORREMOVING LIQUIDS FROM ELASTOMERIC POLYMERS CROSS REFERENCE TO RELATEDAPPLICATION This application is a continuation-in-part of copending US.Pat. application, Ser. No. 753,647 filed Aug. 19, 1968 now Pat. No.3,574,891, and assigned to the assignee of this application.

BACKGROUND OF THE INVENTION The invention relates generally to a methodand apparatus for the removal of liquids, water, various hydrocarbons,etc., both in liquid and vapor phase, from elastomeric polymericmaterial. In the context of the present description, such materials asnatural and synthetic polymers, some of which may include water or otherliquids in their natural state, or as the result of production processesfor the manufacture of synthetic polymeric materials, are the types ofmaterials from which liquid or vapor is removed. The apparatus providedby the invention is generally classified as a continuous mechanicalscrew press, capable of continuous, as distinguished from batch type,operation on the polymeric materials to remove essentially all traces ofmoisture from the material, preferably forming a pellet-like porousproduct, which is'suitable for baling, packaging, or further processinginto product form.

Typical prior art devices of this type for removing moisture fromelastomeric polymers are shown in U.S. Pat. No. 3,225,453, issued Dec.28, 1965 and US. Pat. No. 3,382,538, issued May 14, 1968. Both of thesepatents are assigned to the assignee of this application. A furtherimprovement in such devices is disclosed in US. Pat. No. 3,518,936,issued July 7, 1970, which discloses an adjustable mid-press'annularchoke member, particularly useful in controlling the location within thepress where liquid and/or vapor are removed from the material, in orderto optimize such removal of liquid and vapors. In parent US. Pat.application, Ser. No. 753,647 now Pat. No. 3,574,891, a press having afirst section generally similarto that shown in said US. Pat. No.3,225,453 is arranged to discharge through a tapered conical sleeve intoan extruder sleeve arrangement which is attached to the end of thepress, beyond the tapered sleeve, thereby functioning to extrudeessentially dry polymeric materials through a die plate. A rotatingcutter cooperates with the die plate to separate the extruded materialinto suitable pellet form.

If asubstantial amount of liquid, such as retained water, remains in thematerial as it discharges from a press, there is a rather violent escapeof the liquid. This is due to the large drop in pressure on the heatedmaterial and resultant vaporization of the liquid which explodes throughthe containing mass of material. Depending upon the violence of thisexplosive action, which in turn depends on the amount of liquid presentat discharge, quantities of fine particles (fines") will be formed.These fines become a contaminant from the standpoint that they stick toadjacent surfaces, tend to absorb condensate, and/or degrade fromprolonged contact with hot surfaces, then build uP to the point wherechunks of accumulated fines break loose and fall into the usefulproduct.

SUMMARY OF THE INVENTION In accordance with the invention, portions ofwhich are dis closed in said parent U.S. application, Ser. No. 753,647,the polymeric material is advanced through a screw press cage providedwith a substantial number of drainage or vent openings, preferably asfine slots between screen bars mounted in adjoining relation around allor portions of the cage. Within this cage a series of interrupted screwflight members are arranged on a rotatable shaft. These screw flightmembers are adapted to propel the material through the cage, and some orall of the screw flights may be notched or slotted topromotefurtherworking of the material as it is compressed and propelled through thecage. The screw flight members are separated bycollars'which are alsocarriedon the shafts, and in the region of the collars there are breakerbars or lugs extending inwardly from the cage wall to impede therotation of the material in the cage, and to cooperate with the screwflight to work the material as it is advanced through the cage.Preferably, the bodies of the screw flight members (or some of them) areof progressively increasing diameter, and those collars between screwflight members having difierent diameters are appropriately tapered toprovide a smooth annular passage of decreasing volume, such that thematerial is compressed as it is worked and advanced through the cage. 1

The final or extruder section is preceded by an inwardly tapered sleevewhich surrounds the final screw flight member of the main worm assembly,and cooperates therewith to direct the material into the extrudersection. This section comprises one or more additional screw flights, ofsmaller diameter, carried on the end of the shaft, and operating withina cylindrical sleeve that extends from the end of the tapered sleeve todischarge of the press, where the die plate is mounted across thecylindrical sleeve. Preferably the interior of the cylindrical extrudersleeve and the outermost edge of the flight in the extruder section arecoated with a hardened material such as Stellite, in order to provide abearing support for the cantilever mounted shaft which is driven fromthefeed end of the press, and which extends through the cage and into theextruder section cylinder, essentially unsupported except for possiblecontact between the walls of the extruder cylinder section and the screwflights operating therein. If it is anticipated that additional shaftsupport will be needed along the cage, suitable bearing bushings can beadded, as disclosed in U.S. Pat. No. 3,276,354. I

The improvement described in this application relates to theconstruction and arrangement, in particular, of the final vented presssection which discharges into the aforementioned tapered sleeve,immediately preceding the extruder section. In this region of the presscage, there is an outwardly tapering sleeve preceded by an adjustableannular choke member, generally of the type disclosed in said US. Pat.No. 3,518,936. Material conveyed through the press cage passes betweenthis adjustable choke member and the tapered collar, and issues as arelatively thin sheet-like ribbon of material into and around thefollowing screw flight member, which has a body of substantially smallerdiameter than the large end of the tapered collar. Thus, the material isadvanced intoan expansion chamber where mechanical pressure on it isreleased, and this chamber is vented to the surrounding atmosphere ofthe press through the aforementioned slots in the walls of the presscage.

The screw flight in this expansion section is of considerably greaterpitch, such that it takes up material and conveys it forward at a morerapid rate through the larger volume of the expansion chamber. Thisscrew flight may be notched to promote working the material in thisregion, to assist the release of encapsulated moisture, vapors, etc.From this long pitch screw flight, material is advanced to a taperedscrew flight which cooperates with the aforementioned tapered sleeve toguide and propel the material into the extruder cylinder section. Thelocation and mounting of the tapered sleeve is such that it may take acertain amount of the longitudinal thrust of the advancing screwflights, andthus relieve the die plate from some of the reaction endthrust from the main worm assembly.

Material passing through the adjustable choke member is formed into arelatively thin sheet which is subjected to a super-heated conditionjust prior to entering the following expansion region, where thepressure on the material is substantially reduced, and moisture orvapors flash off. Thus, in this expansion region or zone there is asignificant reduction in moisture content in the material, and atemperature drop as moisture flashes ofi. Thus cooler material is passedto the following extruder-pelletizer section. By controlling theadjustable choke, the temperature and moisture content of material inthe expansion region can be controlled, thus the degree of flashing atthe extruder section discharge, through the die plate, can likewise becontrolled. This results in a definite reduction in the amount of finesproducedat'the die exit.

In one embodiment of the invention, there is a further annular chokemember, which may be of the fixed variety, located substantiallyupstream of the adjustable choke member and the expansionchamber. Thisupstream choke member functions to create a certain amount of backpressure in the initial stages of the press cage, thereby causing thematerial to be worked effectively through all sections of the cage,promoting evaporation of the vapors in the material, or expression ofliquids from the material with subsequent removal either by drainage orevaporation, thereby contributing to the overall efficiency of themachine. This upstream choke member may be followed by an expansionsection of slightly greater internal volume, if desired.

The die plate preferably is mounted in a housing together with the shaftand drive for the rotatable cutter which cooperates with the exterior ofthe die plate. This housing is suitably hinged to one side of the maincage structure, adjacent the discharge end of the extruder cylindersection. This enables the entire sub-assembly to swing away from thecylinder section, allowing the die plate to be cleaned easily in theevent that some of its apertures might be clogged. In addition, theextruder section, which incorporates a cylinder or sleeve having anessentially cylindrical inner surface and a tapered outer surface whichdecreases in diameter away from its outlet or discharge end. Thisarrangement provides a facility for quick removal of the entire extrudercylinder, in the event that it should become worn by abrasion or thelike, as due to the bearing engagement against the extruder cylinder bythe final extruder worm flights operating within it. This constructionpermits replacement of the extruder cylinder as an independent liner,and also permits easy replacement of the final screw flight members,thus minimizing the amount of down time of the machine while these partsare being replaced.

The object of this invention, therefore, is to provide a novel methodand apparatus, having the features above described, for the removal ofessentially all moisture, vapors, etc. from elastomeric polymericmaterials, and for the subsequent production of suitable porous pelletsor similar configurations from the material, all in a continuousprocess, and with minimum creation of lines in and around the product tominimize contamination of the product.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of ascrew press machine constructed in accordance with the invention withportions broken away and a portion shown in axial cross-section;

FIG. 2 is a fragmentary end view taken from the discharge end of themachine generally along the line 2-2 of FIG. 1;

FIG. 3 is an enlarged section of the die plate;

FIG. 4 is a fragmentary section through the cage, taken generally on theline 4-4 of FIG. 1; and

FIG. 5 is a fragmentary perspective view showing the cutter housing anddrive pivoted to an open position.

DESCRIPTION OF THE PREFERRED EMBODIMENT The screw press shown in FIG. 1includes a base and frame which supports a gearbox housing 12 and anupwardly projecting end support 13. The upper end of the support 13 isalso rigidly connected to the housing 12 by a pair of elongated tiebolts 14. An elongated barrel or cage 15 is supported by the frame andincludes a plurality of drainage sections l6, l7 and an extruderdischarge section 18.

The cage sections 16 and 17 are each formed by a pair of matingsemi-cylindrical parts 20 (FIG. 4) each having a plurality of axiallyspaced arcuate ribs 22 connected by axially extended integral flangemembers 23. Each pair of mating cage portions 20 is rigidly connected bya plurality of tie bolts (not shown) which extend through a series ofaligned holes 24 formed within the flange members 23. The ribs 22 of themating cage portions 20 cooperate to define a cylindrical bore 25, and aplurality of axially extending screen bars 28 (FIG. 4) line the bore 25to define a cylindrical pressing chamber 30. The bars 28 areperipherally spaced by wedge-shaped spacers (not shown) to form narrowaxially extending drainage openings or slots 31 and are retained in eachcage portion 20 by axially extending retaining bars 35 (FIG. 4) havingaxially spaced breaker members 36 projecting radially into the pressingchamber 30.

The section 18 includes a tubular housing 38 having end bushings 39secured to the ends of the housing 38. An imperforate sleeve 44, havinga cylindrical interior and a tapered exterior, is positioned within thebushings and defines a cylindrical chamber 45 which forms an extensionof the pressing chamber 30. The housing 38 is in turn mounted betweenend plates 40 carried on the frame support 13 and on the end of section17. The chamber 45 does not have any drainage openings and is somewhatsmaller in diameter than the pressing chamber 30. A smooth transistionis made from chamber 30 to chamber 45 by an annular sleeve 48 having afrusto-conical inner surface 49.

An inlet housing 55 is mounted on the inlet end of the cage 15 and hasan inlet opening 58 which receives the material to be pressed. Anelongated worm assembly 60 extends through the inlet housing 55 and thechambers 15 and 45 and includes a shaft 62 which is connected to asuitable drive motor 64 through a reduction gear train located withinthe gearbox housing 12.

The worm assembly 60 includes a feed worm 65 mounted to rotate with theshaft 62 and extending through the bottom of the inlet housing 55partially into the first cage section 16. Within the first cage section,mounted on shaft 62 and rotatable therewith, there is a succession oftapered collars 66 and a cylindrical collar 67, between which there aremounted worm members 70 having body portions which correspond indiameter to the larger diameter of the preceding collar, and at leastsome of the worm flights on the worm members are notched as indicated at72. Breaker lugs or bars 36 extend toward the corresponding collars,between the worm flights, to resist rotation of the material with theworms as the shaft is rotated to propel the material through the cage.

Toward the far end of the section 16 there is a tapered collar 75 whichincludes an oppositely tapered downstream edge 76, followed by a wormmember 78 having a flight'of substantially greater pitch than thepreceding worm flights. The body of the worm member 78 corresponds indiameter to the adjoining part of the oppositely tapered collar portion78, thus defining an expansion chamber 80 within the downstream end ofthe cage section 16. Cooperating with the outwardly tapered section ofcollar 75 is a choke or ring member 82 which provides with the collar 75a restricted annular orifice through which all of the material must passin moving into the expansion chamber 80. Preferably the entire length ofthe cage section 16 is constructed with drainage openings between thescreen bars 28, although in some instances it may be desirable to haveportions of this cage section with the spacers omitted between screenbars, or an equivalent construction, to form sections from which nodrainage or venting is available.

The orifice provided between the ring 82 and collar 75 functions tocreate a desired amount of back pressure within the upstream portions ofcage section 16, thus assuring that the material is being properlyworked and dewatered in this section. The material passing through theaforementioned orifices into the chamber 80 is subjected to a decreasein mechanical pressure on passing through the orifice and into theexpansion chamber. This allows the liquid to vaporize at the lowerpressure, due to the previous working and heating of the liquidcontaining material to a superheated condition. The longer pitch wormmember 78 carries this material upward toward the end of the cagesection 16, and around the cylindrical collar 69, assuring that there isalways somewhat of a void in the expansion chamber 80 to allow thematerial to expand as it is being worked by the flight of the wormmember 78 and promoting the venting and flashing or draining of pocketsof moisture from the material.

The material is conveyed into the cage section 17, where it is picked upby the first worm member and then conveyed by a succession of wormmembers 86, some of which may have notched flights as shown, past afirst tapered collar 87, and subsequent cylindrical collars 88. Again,breaker bars 36 extend toward the collar for the same purpose aspreviously mentioned.

The material then passes over an oppositely tapered collar and is pickedup by a worm member 92 of smaller diameter operating within a movablering or choke member 95. This ring member is movable axially of the wormassembly, toward and away from a tapered collar 96, to provide anadjustable orifice 98 through which all of the material must pass. Thering member can be moved longitudinally toward and away from collar 96,by reason of its threaded connection 100 with a control gear 102 that isrotated by a pinion 103 driven from suitable reduction gears 104 and amotor (not shown) or some other source of power. Details of such anadjustable ring member are more fully described in said U.S. Pat. No.3,518,936.

A worm member follows the tapered collar 96, and may have a notched wormflight and a body of substantially less diameter, providing an expansionchamber 112 which extends pasta short cylindrical collar 114 to atapered worm member 115 that operates within the tapered collar 49 atthe exit from the cage section 17. The adjustable ring member 95provides a close control over the size of the orifice 98. The pressureexerted upon the material in this region, followed by the expansion ofthe material in the chamber 112 and the working of the material by thenotched flights of the worm member 110, in turn provides a precisecontrol over the amount of moisture in the material, enabling theapparatus to reduce the moisture at this point to nearly 1 percent. Theresultant flashing and venting of moisture in the region of theexpansion chamber 112, whichis surrounded by spaced screen bars aspreviously described,.promotes cooling of the polymeric material, andassures that the material is kept within the desired temperature limitsas it is fed into the extruder section 18 with little or no moistureremaining.

Following the tapered worm member 115, the shaft carries and drives,within the sleeve 44, a first worm member 120, followed by a shortcylindrical collar 122, and a second worm member 125 at the end of shaft62, and preferably having a double helical flight near its dischargeend. A breaker pin 127 is supported by a fitting 128 in the housing 38,and extends through the sleeve 44 toward the collar 122. This pin mayinclude a thermocouple for indicating temperature of the material atthis location. Preferably, the outer peripheral surfaces of the flightsof worm members and are hard coated (as with Stellite) and ground toform a close fit with the inner cylindrical surface of the sleeve 44,thereby providing a bearing support for the discharge end of the wormassembly.

A circular die plate 130 (FIGS. 1, 3 and 5) is mounted on member 40 by aseries of screws 131 and includes an annular array of nozzle orifices134 each defined by a removable plug 135 (FIG. 3) which seats within acounterbore and extends axially to a flat annular face 136. Referring toFIG. 3, the die plate 130 includes a center plug 138 and a conicalshaped cap 140 which defines a central chamber 142. A pair of radiallyextending passageways 143 are formed within the die plate 130 and areconnected to a pipe line 145 for directing steam into the die plate 130for heating the dieplate to a predetermined temperature. The plugs 135are interchanged with another set of plugs for changing the size of theorifices 134, and the die plate 130 may be supported by a hinge toprovide for swinging the die plate open after the screws 131 are removedand thereby provide for convenient interchanging or cleaning of theplugs 135.

A housing is pivotally connected to the end member 13 by a hinge (FIG.2) which includes a pivot pin 152 projecting through aligned holesformed within intertitting ears 153 and 154 secured to the frame member13 and housing 100 respectively. Referring to FIG. 1, the housing 100defines a generally square discharge chamber 155 having :a bottom outlet156. A shaft is rotatably supported by a bearing assembly 162 mounted onthe housing 150, and the forward end portion of the shaft extendsthrough the chamber 155 to support a rotary cutter 165 which is securedto the end of the shaft 160 by a series of screws 166 (FIG. 5). Thecutter 165 includes a plurality of peripherally spaced radiallyextending knives 168 which are positloned in close spaced relation tothe face 136 of the die plate 130 for rotation past the dischargeorifices 134.

A motor 170 is mounted on the housing 150 and has an output shaftconnected by a V-belt drive 172 to the rearward end portion of the shaft160 for rotating the cutter 165. Referring to FIG. 2, the housing 150 issecured to the upright end member 13 of the frame 10 by a series ofscrews 174. When it is desired to remove the die plate and/or thecutter, however, the screws 174 are removed and the housing 150 ispivoted or swung to an open position as shown in FIG. 5 where the cutteris retracted from the die plate 130.

The support for the die plate 130 and the cutter 165 provides animportant feature of the invention. By mounting the die plate 130 on thedischarge end of the cage and by mounting the cutter 165 on the end ofthe motor driven shaft 160 which is supported by the pivoting housing150, the cutter 165 can be easily and quickly moved to a retractedposition (FIG. 5) where both the die plate and the cutter areconveniently accessible for removal or service. This feature isespecially desirable when it is desired to interchange die plate plugs135 to increase or decrease the size of the discharge orifices 134 or toremove the cutter 165 for sharpening the blades 168. Furthermore, bydriving the screw assembly 60 from its feed end and by rotatablysupporting the discharge worm 125 with the sleeve 44, it is unnecessaryto extend the shaft 62 through the die plate with the result that thereis no annular clearance gap through which the material might beextruded.

The pivotal connection between the housing 150 and the frame 10,provided by the hinge mounting, also provides for maintaining a precisepredetermined clearance between the die plate face 136 and the knives168 of the cutter 165 after one die plate is interchanged with anotherdie plate of the same thickness. Furthermore, the bearing assembly 162and motor 170 may also be mounted on ways secured to the housing 150 andbe axially adjustable by a lead screw so that the clearance between theknives 168 and die plate face 136 may be adjusted during operation tocompensate for thermal expansion. t

A significant feature of the invention concerns the location of theadjustable ring 95 and the cooperating collar 96, providing a restrictedorifice upstream of the vented expan sion chamber 112. The material,which is heated by working in the preceding sections of the press, issubjected to the highest pressure in passing through this orifice, aheadof the vented expansion chamber and the discharge from the pressingsection. Practically all remaining moisture in the material is removedby reason of the decreased pressure on the heated material as it isforced through this orifice into the expansion chamber. Remainingmoisture is flashed off at this point and rapidly vents through theopenings of the walls of the expansion chamber. The worm within theexpansion chamber may be notched to work the material in this region andassure that most, if not essentially all, moisture is freed at thispoint. In addition, this worm has a flight of greater pitch, to carrythe material through the expansion chamber at a greater rate than it isentering past the orifice. The vent openings from the expansion chamberare through the spaces between screen bars, thus all solid material isreadily contained in the chamber, while liquids and gases or vaporsescape.

Therefore, as the material enters the extruder section, it has beencooled by reason of the expansion and flashing off of essentially allremaining moisture within the expansion chamber. As the material isforced through the die, and cut into pellets or the like, there islittle if any moisture remaining, and hence little moisture as thematerial is discharged from the die. This avoids any excessive explosiveflashing of moisture as the material leaves the die, and has been foundto reduce significantly the amount of fines which otherwise result whenmaterial containing substantial moisture is forced through a die and isreleased in an explosive manner. The subsequent reduction in fines,practically eliminating them, represents a significant advantage in thehandling of the finished product, and also is a great advantage from thehousekeeping or maintenance standpoint, since the fines tend to cling toall parts of the machinery, become contaminated, and to build up to thepoint where the apparatus must be shut down for cleaning or else thiscontaminated material will fall off into the product.

While the method herein described, and the form of apparatus forcarrying this method into efiect, constitute preferred embodiments ofthe invention, it is to be understood that the invention is not limitedto this precise method and fonn of apparatus, and that changes may bemade in either without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. In a mechanical screw press for expressing liquid from an elastomericmaterial and including a cage having means defining an elongatedpressing section with an inlet end and a discharge end, means formingfluid vent openings extending through at least portions of said pressingsection, a closed extruder section receiving the material from thedischarge end of said pressing section and having a discharge openingfrom the cage, a rotatable screw assembly extending through said cageand including a series of longitudinally spaced spiral flights separatedby collars, means for rotating said screw assembly, means forprogressively compressing material within said pressing section as itmoves toward said discharge end and then through said extruder sectionin response to rotation of said screw, and breaker bar means supportedby said cage and including portions projecting into said pressingsection between said flights to resist rotation of the material withsaid flights as the material is being compressed over said collars, theimprovement comprising a ring member mounted upstream of the dischargeend of said pressing section adjacent one of said collars andcooperating with said one collar to define a restricting orifice, andmeans forming an expansion chamber within said pressing section betweensaid restricting orifice and said discharge end of said pressingsection, said expansion chamber having fluid vent openings thereinwhereby the liquid content of the material is significantly reduced byflashing from the material prior to said extruder section.

2. A press as defined in claim 1, including means for varying the areaof said restricting orifice to achieve optimum liquid removal andtemperature reduction ahead of said extruder section.

3. A press as defined in claim 1, including a die mounted at saiddischarge opening of said extruder section.

4. Apparatus as defined in claim 1, including vent openings upstream ofsaid restricting orifice for initial flashing and/or draining of liquidfrom the material as it is initially being worked.

5. In a mechanical screw press for expressing liquid from an elastomericmaterial and including a cage having means defin ing an elongatedpressing section with an inlet end and a discharge end, means formingfluid vent openings extending through a major portion of said pressingsection, a closed extruder section receiving the material from thedischarge end of said pressing section and having a discharge openingfrom the cage, a rotatable screw assembly extending through said cageand including a series of longitudinally spaced spiral flights separatedby collars, means for rotating said screw assembly, and breaker barmeans supported by said cage and including portions projecting into saidpressing section between said flights to resist rotation of the materialwith said flights as the material 18 being compressed over said collars;the improvement comprising an adjustable ring member mounted upstream ofthe discharge end of said pressing section surrounding one of saidcollars and cooperating with said one collar to define a restrictingorifice, and means forming an expansion chamber within said pressingsection between said restricting orifice and said discharge end of saidpressing section, said expansion chamber having fluid vent openingstherein of small cross-section to contain the material whereby theliquid content of the material is significantly reduced by flashing fromthe material prior to said extruder section.

* IF i

1. In a mechanical screw press for expressing liquid from an elastomericmaterial and including a cage having means defining an elongatedpressing section with an inlet end and a discharge end, means formingfluid vent openings extending through at least portions of said pressingsection, a closed extruder section receiving the material from thedischarge end of said pressing section and having a discharge openingfrom the cage, a rotatable screw assembly extending through said cageand including a series of longitudinally spaced spiral flights separatedby collars, means for rotating said screw assembly, means forprogressively compressing material within said pressing section as itmoves toward said discharge end and then through said extruder sectionin response to rotation of said screw, and breaker bar means supportedby said cage and including portions projecting into said pressingsection between said flights to resist rotation of the material withsaid flights as the material is being compressed over said collars, theimprovement comprising a ring member mounted upstream of the dischargeend of said pressing section adjacent one of said collars andcooperating with said one collar to define a restricting orifice, andmeans forming an expansion chamber within said pressing section betweensaid restricting orifice and said discharge end of said pressingsection, said expansion chamber having fluid vent openings thereinwhereby the liquid content of the material is significantly reduced byflashing from the material prior to said extruder section.
 2. A press asdefined in claim 1, including means for varying the area of saidrestricting orifice to achieve optimum liquid removal and temperaturereduction ahead of said extruder section.
 3. A press as defined in claim1, including a die mounted at said discharge opening of said extrudersection.
 4. Apparatus as defined in claim 1, including vent openingsupstream of said restricting orifice for initial flashing and/ordraining of liquid from the material as it is initially being worked. 5.In a mechanical screw press for expressing liquid from an elastomericmaterial and including a cage having means defining an elongatedpressing section with an inlet end and a discharge end, means formingfluid vent openings extending through a major portion of said pressingsection, a closed extruder section receiving the material from thedischarge end of said pressing section and having a discharge openingfrom the cage, a rotatable screw assembly extending through said cageand including a series of longitudinally spaced spiral flights separatedby collars, means for rotating said screw assembly, and breaker barmeans supported by said cage and including portions projecting into saidpressing section between said flights to resist rotation of the materialwith said flights as the material is being compressed over said collars;the improvement comprising an adjustable ring member mounted upstream ofthe discharge end of said pressing section surrounding one of saidcollars and cooperating with said one collar to define a restrictingorifice, and means forming an expansion chamber within said pressingsection between said restricting orifice and said discharge end of saidpressing section, said expansion chamber having fluid vent openingstherein of small cross-section to contain the material whereby theliquid content of the material is significantly reduced by flashing fromthe material prior to said extruder section.